Shader does not render correctly until rl.DrawGrid(0, 1.0) is called once

[Gishblade]

I've noticed a weird issue where my shader does not work correctly until rl.DrawGrid(0, 1.0) is called at least once
(it does not need to be called every frame)

Video of Bug:
https://www.youtube.com/watch?v=lKa4bVZqznE

I suspect it is related to how textures get loaded in the shader.

My rendering loop is

for !rl.WindowShouldClose() {
		startThing += stepSize
		rl.BeginDrawing()
		{
			rl.ClearBackground(rl.RayWhite)
			rl.BeginMode3D(camera)
			{
				if frameCount == 100 {
					rl.DrawGrid(0, 1.0)
				}
				if modelCase == 2 {
					rl.SetShaderValueTexture(shader, primaryShaderLocation, texture)
					rl.SetShaderValueTexture(shader, dfLocation, linework)
				}
				for i := 0; i < numThingsToSpawn; i++ {
					sin := float32(math.Sin(startThing+float64(i)*fnMult)) * float32(radGrowth) * float32(i)
					cos := float32(math.Cos(startThing+float64(i)*fnMult)) * float32(radGrowth) * float32(i)
					if sin == cos && sin != cos && maxHeight == 30 {
						break
					}
					rl.DrawModel(model, rl.Vector3{X: cos, Z: sin, Y: maxHeight - float32(i)*(maxHeight/float32(numThingsToSpawn))}, 1.0, rl.White)
				}
			}
			rl.EndMode3D()
			rl.DrawFPS(20, 20)
		}
		rl.EndDrawing()
		frameCount++
		if frameCount >= frameTarget {
			break
		}
	}

when modelCase != 2 it does not use my shader at all, and code works as expected (even when not calling rl.DrawGrid(0, 1.0).

My custom shader is

#version 330

// Input vertex attributes (from vertex shader)
in vec3 vertexPos;
in vec2 fragTexCoord;
in vec4 fragColor;

// Input uniform values
uniform sampler2D texture0;
uniform sampler2D distance_field;
uniform sampler2D overwrite_tex;

uniform float divider = 0.5;

out vec4 finalColor;

void main()
{
//    float smoothing = 1.0 / 38.0;
    float smoothing = 1.0 / 18.0;
    float center = 0.65;
    vec4 color = texture(overwrite_tex, fragTexCoord);
    // Place fragment code here.
    float df_alpha = texture(distance_field, fragTexCoord).a;
    if (df_alpha == 0) {
        finalColor = color;
    } else {
        float dfv = df_alpha / 2.0 + 0.5;
        float sstep = smoothstep(center - smoothing, center + smoothing, dfv);
//        float sstep = 0.0;
        finalColor = (1.0 - sstep) * color + sstep * vec4(0.0, 0.0, 0.0, 1.0);
    }
}

Importantly, if I change

vec4 color = texture(overwrite_tex, fragTexCoord);
....
float sstep = smoothstep(center - smoothing, center + smoothing, dfv);

to

vec4 color = texture(texture0, fragTexCoord);
....
float sstep = 0.0;

It renders the models original texture (what is being passed by texture0) just fine.

So the issue seems to be that it does not load the

uniform sampler2D distance_field;
uniform sampler2D overwrite_tex;

arguments correctly until after rl.DrawGrid(0, 1.0) is called for some reason.

[Gishblade]

Oh, and important to note that this bug is present for versions v4.5.0 and v5.0.0 of this binding.

github.com/gen2brain/raylib-go/raylib v0.0.0-20230511170620-d84e4cc82f8d // indirect - version 4.5.0
github.com/gen2brain/raylib-go/raylib v0.0.0-20231123174446-48309e2407b7 // indirect - version 5.0.0.

Unsure if it is an issue with the bindings or raylib.

[JupiterRider]

@Gishblade Maybe you are missing a rl.Begin and rl.End?

[Gishblade]

I've got the Begin/End for both BeginDrawing and BeginMode3D.

I don't think there's a third one needed?

[gen2brain]

Is this an issue with just the Go bindings or Raylib in general?

[JupiterRider]

// Draw a grid centered at (0, 0, 0)
void DrawGrid(int slices, float spacing)
{
    int halfSlices = slices/2;

    rlBegin(RL_LINES);
        for (int i = -halfSlices; i <= halfSlices; i++)
        {
            if (i == 0)
            {
                rlColor3f(0.5f, 0.5f, 0.5f);
                rlColor3f(0.5f, 0.5f, 0.5f);
                rlColor3f(0.5f, 0.5f, 0.5f);
                rlColor3f(0.5f, 0.5f, 0.5f);
            }
            else
            {
                rlColor3f(0.75f, 0.75f, 0.75f);
                rlColor3f(0.75f, 0.75f, 0.75f);
                rlColor3f(0.75f, 0.75f, 0.75f);
                rlColor3f(0.75f, 0.75f, 0.75f);
            }

            rlVertex3f((float)i*spacing, 0.0f, (float)-halfSlices*spacing);
            rlVertex3f((float)i*spacing, 0.0f, (float)halfSlices*spacing);

            rlVertex3f((float)-halfSlices*spacing, 0.0f, (float)i*spacing);
            rlVertex3f((float)halfSlices*spacing, 0.0f, (float)i*spacing);
        }
    rlEnd();
}

@Gishblade
I think you missed a Begin() and End(), which is the Go call for rlBegin and rlEnd. This is what DrawGrid does internally as well.

@gen2brain
Think this issue can be closed then.

[Gishblade]

oh, so in my case raylib needs

rl.Begin()
rl.BeginDrawing()
rl.BeginMode3D()

to render correctly, and the examples mostly get away without explicitly calling rl.Begin() because they happen to call DrawGrid() which calls into rl.Begin()

?

[Gishblade]

Is it intended for users to call rlBegin() themselves?

I don't see a Begin() method in the cheetsheet (just BeginDrawing, BeginMode2D, BeginMode3D, etc.)
suggesting it's supposed to be for internal use?

[JupiterRider]

rlBegin() is part of rlgl. rlgl is a low level API for OpenGL.
It's meant to be used by advanced users.